Conversion for centre pull brakes?

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Evil Rabbit

New Member
I fancy fitting a set of Avid Shorty Ultimate cantilever brakes on my On-One Pompi steel frame cyclo-cross bike. However, at the moment it has v-brakes on and no centre-pull boss to guide the cable ?

Whats the best thing to do? Can I buy the cable guides - how do they fit, weld ?

jesse_anthony_jamis_supernova_brake_profile_600.jpg
 
I'm no expert but I think you can get cable hangers that attach to your stem and seat post so no welding would be required I think I saw them on SJS cycles.

Edit: these are the ones.
 

PpPete

Legendary Member
Location
Chandler's Ford
SJS are definitely the best for that sort of thing.

But why those brakes in particular ?
They are expensive - and don't look to me to be as effective as proper wide Cyclo-Cross cantis.
By "wide" I mean what used to be called "Froggleg" style.

Usual recomendation is http://www.chainreactioncycles.com/Models.aspx?ModelID=34583
These look nice too http://www.chainreactioncycles.com/Models.aspx?ModelID=62357

Both use regular V brake pads.

I have an older generation of that style of brake (which uses smooth post style cantilever pads - so slightly less easy to adjust) on my tourer. With Kool-Stop Dual-Compound pads they are extraordinarily effective.
 

John the Monkey

Frivolous Cyclist
Location
Crewe
If the pompino has a drilled fork crown, you can also use one of these;

http://www.dotbike.com/p/6181 (crown mounted brake hanger) - less prone to judder, and better cable routing (ime) than stem/spacer mounted hangers.

Don't forget, YOU NEED TO CHANGE YOUR LEVERS. Unless you have "Mini V" brakes (arm lengths between 85 & 95mm) the levers you have on your bike are designed for V brakes (assuming the spec on On One's website is right, they're Dia Compe 287V, which will not work well with other sorts of brake).

On the brakes - you can get an awful lot of power (probably more than you can from wide profile) from the low profile "shorty" type brake. The downside is that they drift out of adjustment quickly, and the more power you want, the closer they have to be to the rim to stop the lever bottoming out on your bars.

On my bike (with Tiagra road levers) the key to getting low profile brakes to work is to junk the included link wire, and use an old fashioned straddle - the ones Tektro use for the CR720 are particularly good, and are available as an aftermarket part on their own. Set the straddle low - again, on my bike, the clamp bolt is level with the lower headset cup. This puts a LOT of mechanical advantage at the lever - because of this, you need to gap the brakes close to your rims. An inflated tyre won't go past my brakes, and the gap doesn't allow the unhooking of the straddle.

For the CR720s, just set the straddle as low as you can. These are nice brakes, but can be a bit hair raising when braking conditions are less than optimal. With my levers, I tend to brake from drops rather than hoods, and they work ok then. If you're braking from the hoods, grab a LOT of lever and pull hard! They may well work better with levers designed for canti brakes though. These don't use up pads as quickly as the Oryx did, and can be gapped further from the rim. Their mechanical advantage actually increases as the pad approaches the rim too, which is nice. You can also do wheel changes without unclamping the straddle or deflating the tyres.

Whatever brakes you get, junk the included pads and use Koolstop Salmon, Fibrax Xtreme, or BBB tristops.
 
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Evil Rabbit

New Member
Thanks for all the replies.

As to why the Avid Shorties - I wanted better brakes than the cheap v brakes I have now (and "yes" am changing the levers and cable). These have good reviews, looks good and would have no issue with my knobbly or road tyres.

I also got recommendations for XTR M970 Vbrakes, which would be easier to fit. Any idea how these calipers might compare with the Avid Shorties?

12936.jpg
 

John the Monkey

Frivolous Cyclist
Location
Crewe
As to why the Avid Shorties - I wanted better brakes than the cheap v brakes I have now (and "yes" am changing the levers and cable). These have good reviews, looks good and would have no issue with my knobbly or road tyres.

Better in what sense?

Better braking on 90% of OEM brakes can be acheived by ditching the included pads. Fit Fibrax Xtreme, Koolstop Salmon, BBB Tristop. If you are unfeasibly rich, fit Swiss stop.

HOWEVER:

The Brakes you have (assuming they *are* mini v's) aren't really designed for V brake levers (assuming your levers are Diacompe 287V[1]).

According to Sheldon Brown, the end result will be;

Direct-pull brake levers used with any other type of brakes will feel nice and solid when you squeeze them, but due to their lower mechanical advantage you'll need to squeeze twice as hard to stop as you should, so unless you are a lightweight rider with gorilla-like paws, this combination isn't safe either.
(This is because your mini-v brake has lower mechanical advantage than a true v-brake).

I also got recommendations for XTR M970 Vbrakes, which would be easier to fit. Any idea how these calipers might compare with the Avid Shorties?

12936.jpg

They should work with your existing levers (assuming they are the Diacompe 287V). XTR have a nifty mechanism that keeps the pad face parallell to the rim as the block wears too, very nifty. I'd still change the pads, mind.

[1] On-One's website says they are, only you know for sure though.

Sheldon Brown Link: http://www.sheldonbrown.com/canti-direct.html
 

John the Monkey

Frivolous Cyclist
Location
Crewe
Thanks, thats very helpful John.

Yes mine currently are mini-v.

Well, if we're right about the levers, that's why your braking isn't so hot!

You don't have to go to the top of the Shimano range for a good v brake, btw - by all means go XT, XTR if you want, but I've fitted Deore, Acera to friends bikes and they work great - easy to set up, and good stoppers. Tektro seem decent too, although I've only used their cantis & caliper brakes, personally.
 
I recntly upgraded my pompino front brakes. Took a different approach though by starting by removing the fork and replacing it with a pompetamine fork so I could fit disc brakes, whilst retining a canti on the rear (frogleggs). Of course a disc wheel is needed too.
Very pleased with the result
 
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